"If you click on the card's name, you can see what the "Fashion Magic Card" looks like!"
"Appendix Card is a card that comes with Shogakukan Magazine and Goods. Everyone, check it out☆"
From osharemajo.com (translated)
Appendix Cards (フロクカード Furoku Kādo), known as Event Cards in Taiwan, are Fashion Magic Cards that do not appear in the main roster and can be obtainable under special circumstances (purchasing a specific Shogakukan magazine, Oshare Fan Book, a movie ticket for Love and Berry Dress Up and Dance! Magic of Happiness, or participating an event (Taiwan only)).
These cards started appearing from 2005 Spring-Summer Collection/Version 2 onwards. They are mostly followed by a series of Dress Up Cards that appeared during the Location Test period or are retextures of other cards from main roster. However, this is interrupted as Hair & Makeup Card and Accessory Card can be part of the Appendix Card.
In Best Collection, these type of cards have a chance of making into the main roster if they're popular enough.